1. Field of the Invention
The invention relates to a method for operating an industrial robot, for the accurate processing of workpieces, especially during spot-weIding, wherein coordinates of processing points or lines are preselected according to a program; the invention also relates to a processing device, especially welding tongs for an industrial robot, adapted to be mounted thereon for the accurate processing of workpieces.
2. Review of the Prior Art
In the processing of workpieces by means of a programmable industrial robot, the procedure is generally first of all to feed to the robot the predetermined processing points on a workpiece according to their coordinates ("teach-in"). To this end, the robot may be moved, manually for example, to each of the processing points. The coordinates of these processing points, which are detected by the robot's own path-measuring system, are then fed to the robot's operating memory. In addition to this manual data-input, manual programming and mechanical programming are possible, but this list is not conclusive.
All of these programming methods are based upon the fact that the workpieces to be processed have very accurateIy defined dimensions and are held for processing in a very accurately defined location. Otherwise it is impossible for the industrial robot to "find" exactly the preselected operating points on the workpiece. Positional inaccuracies, which may be due to dimensional inaccuracies in the workpiece, positioning inaccuracies of the workpiece, or also inaccuracies in the robot itself, lead to defective processing.